Have you compared this to the Sony E888? While the E888 feels flimsy, it does have very nice detail and great highs due to its bio cellulose driver. The E888 is around $75 or so now, however it was once much cheaper.

Many seem to have fit issues with the Sennheiser MX980, so they focus instead on the MX880 or MX580. For the price(around $25) the MX580 is great. The MX880 is well liked except for its volume control, which can sometimes become problematic.

I have heard about E888 fakes. Since it has been discontinued a number of years ago, the E888 supply is drying up. I guess the closest thing to the E888 that is readily available is the Sennheiser MX880. The MX580 is just slightly lower in detail and treble quality than the E888. With headphones and earphones though, a slight improvement might mean a tripling of the price. While reviews rave about the MX980 sound, many complain that is uncomfortable and is too large, while others complain about the price. Sennheiser needs to come out with a version of the MX980 that is smaller, cheaper, and is without the volume control. For the price though, the MX580 at around $25 is a great value. On head-fi one person claimed the MX580 sounds better than the PK1. others there claim that the Sennheiser MX580 is on par with the PK3, while some others claim it beats the PK3 and might be more comparable to the PK2. I haven't heard any of the Yuins, so I can't comment. I guess the MX580 probably isn't in the same league as the OK2, however the MX880 might be.

I would love to see more high quality earbuds, especially lower priced ones. It seems like Sony has pretty much given up on earbud research. A pity, as the E484 and E888 are some of best earbuds ever made. At least Sennheiser seems to be commited to earbuds.